1. Field of the Invention
The present inventive concept relates to a device to inspect a non-pattern wafer, and more particularly, to a device to inspect a non-pattern wafer that detects faults of a non-pattern wafer by applying different reference values to respective regions of the wafer.
2. Description of the Related Art
In general, a semiconductor device is formed by repeating processes of forming a plurality of layers on a wafer and patterning the layers. In this case, if faults, such as particle, voids, dislocations, and the like, which may occur in the process of forming the respective layers, exceeds a predetermined tolerance limit, a bad influence may be exerted upon the quality of a completed semiconductor device.
A device to inspect faults of a wafer so as to prevent in advance the occurrence of such faults is a wafer inspection device. A wafer inspection device may be classified into a pattern wafer inspection device to inspect a wafer on which a specified pattern is formed and a non-pattern wafer inspection device to inspect a wafer on which the specified pattern is not formed.
On the other hand, in a semiconductor process of forming a plurality of layers on a wafer, a layer formed on the wafer may have a non-uniform thickness due to the characteristics of semiconductor equipment, a local stepped portion formed thereon, and different surface roughness of respective regions of the wafer. Also, due to a high-temperature wafer processing, the wafer may get bent.
If the same reference value is applied to the whole regions of a wafer in inspecting a wafer having a local stepped portion formed thereon, a wafer having different surface roughness, or a bent wafer as described above, the fault inspection may be performed in a state where such local characteristics are not considered, and thus it is difficult to obtain a reliable result of inspection. This may cause the inferiority of products.
Accordingly, there is a need for a device to inspect faults of a non-pattern wafer in due consideration of the shape and characteristics of the plurality of layers formed on the wafer, and by using such a device, the reliability of the products can be improved.